During a year of routine use of a 10-kilocurie, gamma-radiation source, operational problems have been encountered in control of radiation levels in nearby areas, control of pH and clarity of the water in the source storage well, breakdown of organic plastics under prolonged irradiation, and a discrepancy between nominal and apparent source strength. A short discussion of these problems and the resulting changes in operational procedures is presented.

Experimental results on the interaction of neutrons with intermediate and heavy nuclei are summarized. Until recently the interaction of nucleons with nuclei has usually been described in terms of the compound nucleus theory. The data presented, however, can not be accounted for by the compound nucleus theory. It appears to be necessary to assume instead that a neutron can traverse a nucleus rather easily with only a small chance of being absorbed into a compound system. Feshbach, Porter, and Weisskopf have proposed an optical potential consisting of a complex square well to account for the experimental data. While this model gives better agreement with the experiments than the compound nucleus theory, it leads to some inconsistencies. In order to be consistent with the results of measurements on neutrons and with the shell model the potential needs to be modified to be deeper than that used by Feshbach et al., and it should contain a spin-orbit coupling term.

A wealth of research potential exists in the independent colleges of the country, yet it has been tapped only to a slight extent in comparison with the way in which the capabilities of the universities have been exploited. To convert this potentiality to actuality, we need financial support of a somewhat different type from that commonly available at present. Some of the conditions which must be satisfied, both by sponsors and by the colleges, are discussed.

The principle of the inertia of energy is a conclusion of the relativitytheory that has far reaching consequences, in that it consolidates the laws of conservation of mass, momentum, and energy into one conservation expression. A brief historical discussion of the conservation laws and of the classical concept of the flow of energy is followed by several mathematical derivations and interesting examples of the inertia of energy. Where possible an heuristic approach is used.

This Association has to its credit many enviable achievements. It is suggested, however, that the present concepts as to its purpose and mission are inadequate for the future. Thus far in its history it seems to have been conceived of mainly an as association to hold meetings, to publish a journal, and to prepare, file, and occasionally publish committee reports. Having in mind the individual teacher, it has tried to give him encouragement, recognition, and inspiration, and opportunities to exchange ideas and experiences with his fellows.

The Association should become, to a much larger extent than in the past, an association for concerted and organized group study and action. Its goal should be to make of physics teaching a profession in the sense that law and medicine are professions. This will require more than that the Association give aid and encouragement to the individual teacher who endeavors to become more effective. It will require planned, systematic, and united attacks upon the problems of the profession as a whole and cooperative attempts to find solutions to such problems. It will require that the Association assert itself as the authoritative interpreter and official representative of physics teaching before the general public, other professional organizations, and government agencies; constitute itself a potent pressure group in behalf of our profession; help aggressively to maintain high professional standards; help improve conditions under which physics teachers must work; conduct cooperative educational experimentation and systematically attempt to improve physics teaching; collaborate with other agencies of higher education.

The past and current organization and modes of operation of the Association are not especially suitable for the realization of such purposes. Modifications and changes in these areas are suggested.

Although spectacles were invented near the end of the thirteenth century, there is little evidence that concavelenses were generally used to aid the nearsighted before the middle of the sixteenth century. However, Lucas Cranach's “Adulteress before Christ,” painted about 1500, shows a pair of spectacles with lenses which apparently were concave.

The concept of the isotropy of a perfect gas is examined from the point of view of the distribution functions for molecular speed and velocity components. It is shown that to be compatible with the assumption of isotropy, any velocity component distribution function must satisfy several general relations. These relations are often presented as a consequence of the Maxwellian distribution but are shown to be independent of the form of the distribution of molecular speeds.

The classical model for rotational magnetic moments in molecules is useful for elucidating physical description, although it must give way to quantum mechanics for fundamental formulation. A powerful method of approach, first applied to the problem by Wick, is afforded by the generalized theorem of Larmor, which is here derived from the equations of motion for a rotating molecule placed in a magnetic field. It is shown that the electronic motion relative to the nuclear frame must be perturbed by the Coriolistorque as a consequence of molecular rotation. The rotational magnetic moment of the molecular electrons can be considered to consist of two parts, one due to “rigid” motion together with the nuclear frame and the other to “nonrigid” motion, which is equivalent to that created by a magnetic field in a nonrotating molecule according to the relation .

It is shown that for linear undamped motion the dynamic load factor will not exceed 2 when the forcing function is monotone nondiminishing or nonincreasing. Similarly, if the first relative maximum of is its absolute maximum, the dynamic load factor will not exceed 2. A few cases are illustrated for which the load factor ranges between zero and an indefinitely large value.